<!DOCTYPE html>
<html lang="zh-CN">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <script src="vue.min.js"></script>
</head>

<body>
  <div id="app">
    {{object.c.dd}}
    <button @click="numChange()">+1</button>
  </div>

  <script>
    var vm = new Vue({
      el: '#app',
      data: {
        object:{
          a:123,
          b:213,
          c:{
            aa:123,
            bb:421
          }
        }
      },
      watch:{
        object:{
          handler(newval,oldval){
            console.log(1)
          },
          immediate: true,
          deep:true
        }
      },
      created(){
          this.object.c.dd=123
      },
      methods: {
        numChange(){
          console.log(this.object.c.dd)
          this.object.c.dd+=1
        }
      }
    });
  </script>
</body>

</html>